Without limiting the scope of the invention, this background is described in connection with navigational aids. Approximately eight million Americans report having some form of low-vision defined by difficulty reading print material in a typical newspaper with corrective lenses (McNeil, 2001). Common causes of low-vision include (but are not limited to) macular degeneration, glaucoma, and diabetic retinopathy. For example, someone who has age-related macular degeneration may loose vision in the central three degrees of their visual field with the remaining portion of their visual field remaining intact. For people with low-vision, independent navigation and way finding remains a challenge.
Indoor pedestrian mobility can be broken down into two fundamental processes: obstacle avoidance and way finding. Obstacle avoidance is the process of maneuvering around objects within the navigator's immediate vicinity. Although obstacle avoidance is a challenge for someone who is blind or has low-vision, typically they can use their residual vision, a long cane, guide dog or a variety of other obstacle avoidance mechanisms to navigate around obstacles. Furthermore, Pelli (1987) investigated the effect of reduced vision on obstacle avoidance behavior and found that even with significant reduction of visual information subjects were able to maneuver around objects with little difficulty.
For most people with vision loss the primary obstacle to independent mobility lies in the problem of wayfinding in an unfamiliar building. Navigating through a familiar building, such as their home, or the building in which they work, does not pose much of a challenge for someone with low-vision. This is because they have generated a cognitive map (Tolman, 1948) of the environment or an internal representation of this large-scale space. The primary challenge lies in when someone with a visual deficit visits an unfamiliar building.
Many research scientists and engineers have recognized the challenges faced by low-vision navigators. Recently with the public use of global positioning system (GPS) signals, researchers have developed navigation aids for outdoor navigation (e.g., Golledge, Loomis, Klatzky, Flury, & Yang, 1991; Golledge, Klatzky, Loomis, Speigle, & J., 1998; Loomis, Golledge, & Klatzky, 2001, 1999). These systems (e.g., GPS and GPS Talk) can be used to localize the user within a large-city, provide instructions to reach a specific destination in addition to providing information about local points of interests (e.g., “the Museum of Modern Art is to your left”). GPS systems have generated a great deal of excitement and have proven to be effective. However, the utility of GPS-based systems ends at the front door of the building due to the fact that GPS signals are typically unavailable indoors.
Many contemporary buildings have been fitted with Braille signs that identify room numbers and other significant landmarks. However, the utility of these signs is marginal given that they are difficult to localize and studies have shown that many low-vision or blind individuals either do not use Braille or cannot read Braille (Blind, 1999; Goldish, 1967). These studies suggests that not only are these low-vision navigation aids awkward, but they may be ineffective for a large portion of the population that they are intended to help.
A low-vision indoor navigation aide has been developed by Loughborough (1979) which has recently been developed into the Talking Signs® system (Brabyn & Brabyn, 1982, 1983). The Talking Signs® system uses beacons that transmit a modulated infrared light signal that generates a continuous signal. The beacon can be placed at a potential indoor destination (e.g., a door or an elevator) outdoor destination (e.g., a bus stop) or even on a moving bus (Marston & Golledge, 1988). The user carries a small hand-held receiver that when pointed in the general direction of the transmitter, translates the modulated infrared light signal into speech output.
Another low-vision navigation aid is the Verbal Landmarks® system, which also uses a series of beacons similar to the Talking Signs® beacons. Verbal Landmarks® beacons use an inductive loop system that is activated when a portable receiver is within range (approximately 5 feet). When activated, a verbal message, the Verbal Landmarks® can be heard, however the Verbal Landmarks® system signal is non-directional, therefore, the auditory messages for the Verbal Landmarks® are usually different than those used for the Talking Signs®. The Talking Signs® typically announce the room number or landmark (“Bus Stop”) and allows the user to use this information to navigate. By contrast, the Verbal Landmarks® will give instructions to specific goal states (e.g., “The bathroom is North 5 steps and to the right” as described in, Bentzen & Mitchell, 1995).
Bentzen and Mitchell (1995) investigated the efficacy of Talking Signs® versus Verbal Landmarks® in a real environment (at the Annual Convention for the American Council of the Blind held in a hotel conference center). In these studies, Bentzen and Mitchell (1995) participants were given a collection of routes to follow during the conference. Bentzen and Mitchell (1995) found a significant advantage in both distance traveled and the time to complete the routes for participants that used the Talking Signs® over those that used Verbal Landmarks® The work by Bentzen and Mitchell (1995) showed empirically that Talking Signs® are a more effective system. Although the Talking Signs® low-vision orientation aid performed better than the Verbal Landmarks® system, the Talking Signs® system has not been accepted broadly as a solution to the low-vision wayfinding challenge.
One reason for the lack of adoption may lie in the cost associated with adopting the system. For example, the beacons for the Talking Signs® system cost approximately $2,000 each. If the average building required 250 beacons (the number of beacons installed at the San Francisco City Hall) at $2,000 per beacon, the cost to retrofit an average building would be $500,000. It should be pointed out that for the same amount of money, one could hire a dedicated “low-vision escort” for $25,000 per year who would wait at the front of the building and escort any low-vision visitor to their destination for 20 years before exceeding the cost of the initial installation costs of the Talking Signs®. In order for a low-vision navigation aid to be accepted by the blind and low-vision community, most buildings should possess this technology. In order for a system to be ubiquitous, it must be inexpensive to install and use. The anticipated cost for adopting the system would be negligible from the perspective of building management (on the order of $5,000 to $10,000) and the cost of the handheld navigation system could be on par with a high-end digital magnifier (about $2,000).
As a result, there is a need for a system, apparatus and method of improving navigation for low-vision, blind and potentially, normally sighted users in unfamiliar buildings using a navigation aid that guides and orients a user within an unfamiliar indoor environment and provides instructions to a desired location.